Lactobacilli inhibit Shigella dysenteriae 1 induced pro-inflammatory response and cytotoxicity in host cells via impediment of Shigella-host interactions

Objective: Shigella dysenteriae Type 1 dysentery is a major cause of morbidity and mortality in children from less developed and developing countries. The present study explores the hypothesis that lactobacilli protect the host cell during S. dysenteriae Type 1 infection and its mechanism of action. Methods: Caco-2 cells incubated for 1 h with Lactobacillus rhamnosus or Lactobacillus acidophilus at the multiplicity of infection of 100, either alone or in combination followed by addition of Shigella at the same multiplicity of infection for 5 h served as treatment groups. Cells incubated with Shigella without lactobacilli addition served as infected cells. At the end of experimental period, cells were processed suitably to enumerate adherent and internalized Shigella. Reverse transcription-polymerase chain reaction was performed to assess mRNA expression of interleukin-8 and tumour necrosis factor-a. Immunoblot for heat shock protein-70 and cytotoxicity assay were performed. Results: Pretreatment with the combination of lactobacilli significantly (p <0.05) prevented adherence and internalization of Shigella coupled with reduced expression of tumour necrosis factor-cc and interleukin-8 in host cells. Conclusion: L rhamnosus and L acidophilus, synergistically offered better protection during S. dysenteriae Type 1 infection by efficiently inhibiting adherence and internalization of Shigella coupled with inhibition of pro-inflammatory response. (C) 2009 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.